Final answer:
A new type of bacteria that turns purple with Gram stain likely belongs to the Proteobacteria lineage, which includes purple sulfur Gammaproteobacteria that obtain their color from pigments.
Step-by-step explanation:
If a new type of bacteria turns purple when treated with Gram stain, it likely belongs to the Proteobacteria lineage. Purple bacteria and their relatives, which turn purple due to their pigments such as bacteriochlorophylls and carotenoids, have been classified under the phylum Proteobacteria. This phylum is a large and diverse group of gram-negative bacteria and includes many bacteria that are part of the normal human microbiota as well as numerous pathogens. Notably, bacteria of the genus Chromatium are purple sulfur Gammaproteobacteria, a class within the Proteobacteria phylum.